Apparatus for bicycle transmissions are numerous. A traditional apparatus employs a chain for driving a rear gear from the force exerted on a front gear by a human. The primary advantage of a chain is that it is strong, assures drive because of the teeth and comprises chain pins which permit the use of a small rear derailer. The primary disadvantage of a chain is the weight of the chain and the weight of the metal gears associated therewith.
Several persons have disclosed belt drive transmissions, but these systems are more complicated than traditional chain apparatus. See for example Maguire (U.S. Pat. No. 5,054,801) and Stuhler (U.S. Pat. No. 5,061,224).